This invention relates generally to industrial type burners, and more particularly to fuel intake provisions to industrial type burners.
Industrial type burners with a high-BTU capacity typically work on a comparatively volumous gaseous throughput, and they can become generators of significant amounts of air pollutants if they are improperly adjusted. The burner design specifications are such that the operation of these burners would at least seek to meet specified maximum levels of nitrous oxides and unburned hydrocarbons in combustion gas emissions. State of the art burners usually can be adjusted to optimize both nitrous oxide and unburned hydrocarbon levels of emissions down to acceptable levels. Often, however, an adjustment to minimize burner emissions with respect to of either one of the pollutants does not coincide with an optimum adjustment for minimum emission level of the other of the pollutants. Thus, for most burners, optimum adjustments of such variables as fuel to air ratios, excess or secondary air induction, or pressure levels of turbo air used as primary combustion air is, at best, a compromise. An optimum burner adjustment hopefully reduces both the nitrous oxide and hydrocarbon emissions to levels which meet prescribed requirements.
A known process of enhancing the mixture of fuel with combustion air in burners is to use relative motion between the fuel and the combustion air. A known axial flow turbo-burner type uses a swirling stream of combustion air into which fuel is injected to enhance mixing of the fuel with combustion air, which, in turn, tends to reduce pollutant levels in the effluent gases. U.S. Pat. No. 5,192,204 to Musil teaches dispersing, for example, liquid fuel by compressed air to initially atomize the fuel. The atomized fuel is then introduced into a flame region of a burner. Upon entering the flame region, the atomized fuel becomes entrained in a conically expanding pattern of a first stream of primary combustion air. The first stream of primary combustion air is then further mixed with a variable second stream of combustion air. Successive steps of mixing the fuel with combustion air and the mixture with further combustion air appears to improve fuel-air mixtures and the quality of emissions. However, meticulous adjustments of each of the various air streams may be needed to optimize pollutant levels and maintain combustion emissions under control. With continued emphasis on cutting down on air pollution, even in those industries which necessarily use high-output industrial burners, such as in aggregate and asphalt plants, further efforts are needed to make it easier to reduce pollutant generation by these burners.